State highway codes of all the states contain legal weight limits for vehicles using the respective roads. These weight limits are established to prevent damage to the pavement and roadbed as well as for safety reasons. The weight limits are normally defined in terms of the maximum allowable pay load for each axle of the vehicle. Most states have check stations along the highways at key points to detect violations of any legal weight limit. The vehicles are required to be driven onto scales wherein the weight limit on each axle is determined. It is possible that the total weight contained within the motor vehicle is within limits. However, the load may be so unbalanced as to cause an overweight on one or more of the axles. If a vehicle is found to be illegally loaded, it is detained until another vehicle can be dispatched to remove part of the load. In addition, the driver is normally fined.
Trucking companies as well as drivers desire to load as much cargo into the truck as legally permissible for economic reasons. Drivers have for the most part learned to balance a load within their trucks. This is gained by experience. Many drivers have learned it is difficult to load a vehicle in a balanced manner. Generally, there is a certain degree of trial and error imposed. Any mistake can be costly. Accordingly, most drivers tend to underload their vehicles.
The need for an overload indicator has been recognized. Various people have attempted to devise idicator devices which can be permanently attached to a vehicle bed so as to determine when a preset load level has been approached or exceeded. Known overload indicator devices are primarily comprised of two parts. One part is attached to the underside of the motor vehicle while the second part is attached to the axle. As additional weight is added to the vehicle, the bed is gradually forced downward until a pre-set limit has been exceeded. At that point contact points of the indicator device touch and set off an alarm of some type. A major draw back with devices of this type is that even though a motor vehicle has been loaded and balanced so as to be within legal limits false readings can occur as the vehicle travels down the road. Unevenness of the surface roadways will cause a certain degree of bouncing of the vehicle. This bouncing will cause the springs to compress and, in effect, cause the contact points of the indicator device to come together and set off the alarm. This false reading can be very annoying to the driver. An on/off switch in the cabs on the motor vehicles has been provided to avoid this. This does avoid one problem; however, the life of the indicator device is substantially reduced when such inadvertent contacts are continually made.
There is a definite need for an axle weight overload indicator device. Such a device must be easy to install and provide accurate readings. The device must also be built so as to withstand continued use over a long period of time. In accord with this need, there has been developed an axle weight overload indicator device.